Adhesive paint film

ABSTRACT

Adhesive coating film consisting of 
     a) a radiation-cured coat which comprises 
     from 40 to 90% by weight, preferably from 50 to 60% by weight, of urethane acrylate, 
     from 0 to 20% by weight, preferably from 10 to 15% by weight, of polyether acrylate, 
     from 10 to 50% by weight, preferably from 25 to 40% by weight, of reactive diluent, 
     from 0 to 30% by weight of pigments 
     from 0 to 10% by weight, preferably from 2 to 5% by weight, of a carboxy-functional (meth)acrylic esther [sic], 
     from 0 to 10% by weight of other customary coatings fillers, and 
     in the case of curing with UV radiation, from 0 to 10% by weight, preferably from 3 to 6% by weight, of photoinitiator, and 
     b) which carries on one side an adhesive composition which 
     has free NCO groups in the freshly applied adhesive composition, 
     can be plastified thermally, especially under the intended processing conditions, and 
     has a markedly weak surface tack.

BACKGROUND OF THE INVENTION

The invention relates to an adhesive coating film and to itspreparation.

Adhesive coating films are known. For instance, German Utility Model 7241 096 describes a self-supporting, flexible coating lamina in web orsheet form, which may be provided on one side with a self-adhesivecomposition, and is covered with a release paper (p. 2, middle), usebeing made of conventional self-adhesive compositions based onrubber/resin or acrylate (p. 3, bottom). Although such products avoidconventional coating by brushing or dipping and the problems withsolvents etc. that such coating entails, they nevertheless haveimportant practical deficiencies in terms of their tack, processabilityand stability, and such products have, accordingly, been unable toestablish themselves.

Products of this kind are also described by DE 30 42 156 C2, which infact describes a transferable coating sheet for which acrylate resincoating materials, in particular, are applied to a backing film fromwhich these coating materials can then be transferred to the backgroundthat is to be coated, a waxlike release layer being intended tofacilitate detachment from the backing film, while a self-adheringadhesive is used for bonding the coating material (col. 4, l. 31 ff.).These products too exhibit the above-mentioned deficiencies.

German Utility Model G 81 30 861 discloses a multicoat label whichconsists of one thin and one thick coat, both of which are electronbeam-cured and applied without solvent, the two coats featuring goodcolor contrast. A laser can be used to burn through the upper coat sothat the lower coat becomes visible in a contrast color to the upper, inthe form of a script mark or the like. A label of this kind can be stuckon by means of a pressure-sensitive, hotmelt or reactive adhesive (p. 2,l. 18), preference being given to the use of pressure-sensitiveadhesives. Products of this kind are, however, less suitable for coatingsurfaces.

EP 230.364 B1 discloses laminates for the transfer of coating materials,in which an at least partly heat-activatable adhesive is employed,having a specific glass transition point and modulus of elasticity. Adisadvantage of these products is that they are not radiation-curable.

In addition, EP 283.651 B1 describes coats and coating sheets where thecoating material is applied in two or more layers to aradiation-permeable plastic film and is cured by irradiation throughthis film. These coating sheets of highly complex configuration can beprovided with an adhesive layer (p. 4, l. 22/23) comprising freechemically reactive groups and synthetic resin or plastic, especiallywith a mixture of polyisocyanate and hexamethylenetetramine and anOH-containing PVC copolymer (p. 5, l. 16-24). Disadvantages of suchproducts can be summarized as follows:

solid colors require a two-coat system.

Topcoats are produced with the solventborne coating materials,

topcoats likewise [sic].

As a result of roller application techniques, a preferential directionof the texturing is unavoidable.

It is impossible to achieve all degrees of matt, since the texturing isproduced by way of the topcoat and is leveled by the application of theprinted layer and of the transparent layer.

The transparent layer is not particularly protected against externalcontamination by the technique. Clean room conditions are required.

EP 547.506 A1 describes a process for coating aluminum in which amultilayer composite is built up on a carrier film. Finally, an adhesivelayer is applied (col. 4, l. 45-53), based on epoxide, polyester,polyurethane, acrylate, urea or the like, with sufficient crosslinkeralso being employed.

SUMMARY OF THE INVENTION

The object of the invention was to provide an adhesive coating filmwhich does not have the disadvantages of the prior art, or at least notto the same extent.

The invention relates accordingly to an adhesive coating film consistingof

a) a radiation-cured coat which comprises

from 40 to 90% by weight, preferably from 50 to 60% by weight, ofurethane acrylate,

from 0 to 20% by weight, preferably from 10 to 15% by weight, ofpolyether acrylate,

from 0 to 10% by weight, preferably from 2 to 5% by weight, of acarboxy-functional (meth)acrylic ester,

from 10 to 50% by weight, preferably from 25 to 40% by weight, ofreactive diluent,

from 0 to 30% by weight of pigments

from 0 to 10% by weight of other customary coatings fillers, and

in the case of curing with UV radiation, from 0 to 10% by weight,preferably from 3 to 6% by weight, of photoinitiator, and

b) which carries on one side an adhesive composition which

has free NCO groups in the freshly applied adhesive composition,

can be plastified thermally, especially under the intended processingconditions, and

has a markedly weak surface tack.

DETAILED DESCRIPTION OF THE INVENTION

In the text below the constituents of the coat and of the adhesivecomposition are described in detail:

Urethane acrylate

The urethane acrylates of the invention consist preferably of from 30 to45% by weight of polyester, with very particular preference from 30 to40% by weight, from 0.01 to 0.1% by weight of catalysts, from 0.05 to0.1% by weight of stabilizers, from 10 to 20, preferably from 15 to 20%by weight of hydroxyethyl acrylate, from 15 to 25, preferably from 15 to20% by weight of reactive diluent and from 20 to 35, preferably from 25to 35% by weight of a diisocyanate component.

The polyesters employed in accordance with the invention consist of from50 to 75% by weight, preferably from 55 to 65% by weight, of alcohol andfrom to 20 to 50, preferably from 30 to 45% by weight of acid and also5% by weight of customary auxiliaries.

The preparation of the hydroxyl-containing polyester resins takes placein a known manner by esterifying polybasic carboxylic acids withpolyhydric alcohols in the presence of appropriate catalysts. Instead ofthe free acid it is also possible to employ ester-forming derivativesthereof. Examples of alcohols suitable for preparing the polyesters areethylene glycol, 1,2propylene glycol, 1,3-propylene glycol,1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol,neopentyl glycol, diethylene glycol, triethylene glycol and also triols,such as glycerol, trimethylolethane, trimethylolpropane andtris-2-hydroxyethyl isocyanurate, for example.

Also suitable are cycloaliphatic alcohols, such as cyclohexanols and1,4-bis(hydroxymethyl)cyclohexane, aromatic alcohols, such as1,3-xylylenediol, and phenols, such as 2,2-bis(4-hydroxyphenyl)propane(bisphenol A).

Preference is given to the use of mixtures of trimethylolpropane,triethylene glycol, cyclohexane-dimethanol.

Also suitable are dihydric aliphatic alcohols, such as 1,4-hexanediol,1,6-hexanediol, 2-methyl-1,5-pentanediol, 2-ethyl-1,4-butanediol.Dimethylolcyclohexane, trihydric alcohols, such as trimethylolbutane,tetrahydric alcohols, such as pentaerythritol, such as [sic] more highlypolyhydric alcohols, such as di(trimethylolpropane), di(pentaerythritol)and sorbitol.

Examples of suitable carboxylic acids are phthalic acid, isophthalicacid, terephthalic acid and their esterifiable derivatives, such as theanhydrides, for example, provided they exist, and the lower alkyl estersof said acids, such as, for example, methyl, ethyl, propyl, butyl, amyl,hexyl and octyl phthalates, terephthalates and isophthalates. Themonoesters, the dialkyl esters and mixtures of these compounds can beemployed. Also employable are the corresponding acid halides of thesecompounds. Preference is given to mixtures of phthalic anhydride,isophthalic acid and adipic acid.

Aliphatic and/or cycloaliphatic diisocyanates are suitable for preparingthe urethane acrylate, examples being 1,3-cyclopentane, 1,4-cyclohexaneand 1,2-cyclohexane diisocyanate, 4,4′-methylenebis(cyclohexylisocyanate) and isophorone diisocyanate, trimethylene, tetramethylene,pentamethylene, hexamethylene and trimethylhexamethylene1,6-diisocyanate, and also the diisocyanates described in EP-A-204 161,column 4, lines 42 to 49, that are derived from dimeric fatty acids.

Preferably, isophorone diisocyanate is added onto the hydroxy-functionalpolyester. By addition reaction of hydroxyl-containing acrylic estersand/or methacrylic esters, such as hydroxyethyl acrylate or hydroxybutylacrylate, with mono- and/or oligomers containing isocyanate groups, thepolyurethane acrylates and/or methacrylates are obtained.

So that no unwanted polymerization occurs in the course of the additionreaction, polymerization inhibitors are generally added, as stabilizers,to the reaction mixture. The suitable polymerization inhibitors includeknown products, such as substituted phenols, such as2,6-di-tert-butyl-p-cresol, hydroquinones, such as methylhydroquinones,and thioethers, such as thiodiglycol or phenothiazine.

Polyether acrylate

The polyether acrylate used in accordance with the invention consists offrom 50 to 75% by weight, preferably from 55 to 65 by weight, of apolyetherpolyol, from 20 to 50% by weight, preferably from 30 to 45% byweight, of acrylic acid, and 5% by weight of customary auxiliaries.

The polyetherpolyols involved preferably have an OHN of 290 mg of KOH/g,a molecular weight of 800 and a viscosity of 500 mPas.

The hydroxyl-containing polyethers which are esterified with acrylicacid and/or methacrylic acid are obtained by reacting dihydric and/orpolyhydric alcohols with various amounts of ethylene oxide by well-knownmethods (cf. e.g. Houben-Weyl, Volume XIV, 2, Makromolekulare Stoffe II,(1963) The ether alcohols employed generally have a degree ofethoxylation of from 10 to 20, preferably from 13 to 17. Preferablyemployed is ethoxylated erythritol with a molecular weight of from 500to 1,000, preferably from 700 to 900. One example is pentaerythritoletherified with 15 etoxy [sic] units.

Reactive diluent

Depending on the viscosity of the esters, the radiation-curable coatingcompositions may comprise reactive diluents, preferably copolymerizablecompounds known for use in radiation-curable coating compositions, forexample (meth)acrylic esters, especially methyl (meth)acrylate, ethyl(meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isopropyl(meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl(meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate,octyl (meth)acrylate, 3,5,5-trimethylhexyl (meth) acrylate, decyl(meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate,octadecenyl (meth)acrylate, phenoxy-ethyl acrylate and the correspondingesters of maleic, fumaric, tetrahydrophthalic, crotonic, isocrotonic,vinylacetic and itaconic acid. Preference is given to the use ofmonomers having more than one double bond per molecule, examples beingethylene glycol diacrylate, diethylene glycol diacrylate, propyleneglycol diacrylate, trimethylene glycol diacrylate, neopentyl glycoldiacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycoldiacrylate, 1,6hexamethylene glycol diacrylate, 1,10-decamethyleneglycol diacrylate, trimethylolpropane triacrylate, pentaerythritoltetraacrylate and pentaerythritol triacrylate, and also thecorresponding methacrylates. Also suitable are the ethoxylated orpropoxylated derivatives, and the long-chain linear diacrylatesdescribed in EP-A-250 631 which have a molecular weight of from 400 to4,000, preferably from 600 to 2,500. The two acrylate groups can beseparated, for example, by a polyoxybutylene structure. Also employableare 1,12-dodecyl diacrylate and the reaction product of two moles ofacrylic acid with one mole of a dimeric fatty alcohol having generally36 C atoms. very particular preference is given to the use of isobornylacrylate, trimethylolpropane triacrylate and acrylic esters ofethoxylated pentaerythritol.

The addition of ethylenically unsaturated compounds controls theviscosity and the curing rate of the coating compositions and also themechanical properties of the resulting coating, as is familiar to theskilled worker and is described, for example, in EP-A-223 086, to whichreference is made for further details.

The photoinitiator, which is customarily employed in the coatingcompositions of the invention in an amount of from 0 to 10% by weight,preferably from 3 to 6% by weight, based on the overall weight of thecoating compositions, varies with the radiation that is employed to curethe coating materials (UV radiation,. electron beams, visible light).The coating compositions of the invention are preferably cured by meansof electron beams. In the case of the use of UV radiation it is commonto employ ketone-based photoinitiators, by way of example acetophenone,benzophenone, diethoxy-acetophenone,2-hydroxy-2-methyl-1-phenylpropan-1-one, hydroxypropyl phenyl ketone,m-chloroacetophenone, propiophenone, benzoin, benzil, benzil dimethylketal, anthraquinone, thioxanthone and thioxanthone derivatives, andtriphenylphosphine and the like, and also mixtures of variousphotoinitiators.

Other additives

The coating compositions may, if desired, also comprise pigments andcustomary coatings fillers, customary auxiliaries and additives. Theformer are employed in amounts of from 0 to 30% by weight. Theproportion of customary coatings fillers is from 0 to 10% by weight.Auxiliaries and additives are usually employed in an amount. of from 0to 4% by weight, preferably from 0.5 to 2.0% by weight, based in eachcase on the overall weight of the coating composition. Examples of suchsubstances are leveling agents, plasticizers, defoamers and, inparticular, adhesion promoters. Adhesion promoters employed here arealkoxysilanes, such as, for example, N-β-aminoethyl-,-aminopropyltrimethoxysilane, -aminopropyltrimethoxysilane,N-methyl-β-aminopropyltrimethoxysilane or triamino-modifiedpropyl-trimethoxysilane (e.g. adhesion promoter DYNASLYAN^(R) [sic],“Type TRIAMO”, commercial product of Dynamit Nobel Chemie).

As additional adhesion promoters it is possible to use from 0 to 10,preferably from 0 to 5% by weight of a carboxy-functional (meth)acrylicester. Examples are β-carboxyethyl acrylate and EBECRYL 169 or 170 whichcan be obtained from UCB, S. A., Drogenbos, Belgium.

Using the coating films

The curing of the coating films is carried out by means of radiation,preferably by means of electron beams. The apparatus and conditions forthese curing methods are known from the literature (cf. e.g. R. Holmes,U.V. and E.B. Curing Formulations fur [sic] Printing Inks, Coatings andPaints, SITA Technology, Academic Press, London, United Kingdom 1984)and require no further description.

The curing of the coating films takes place directly after applicationor following the evaporation of water that is present, by means of UV orelectron beams. The apparatus and conditions for these curing methodsare known from the literature (cf. e.g. R. Holmes, U.V. and E.B. CuringFormulations for Printing Inks, Coatings and Paints, SITA-Technology,Academic Press, London, United Kingdom 1984, pages 79-111) and requireno further description.

The adhesive coating film of the invention is particularly suitable forcoating planar and weakly three-dimensionally formed surfaces using ahot press. In this case there is no use of liquid coating materials oncustomary coating lines and hence no costly measures such as, forexample, recovery or incineration of solvents, and no problems for thehandling, the transportation, the storage and the disposal of hazardoussubstances and for personal protection In comparison with sheet-coatedarticles, there is an increase in the utility and in the nonmaterialvalue thereof through improvement of the thermal stability and chemicalresistance and of the production of a surface having an appearance andfeel typical of a coating. Moreover, there is substantial avoidance ofthe pollution of the air in the room by retained solvents and monomers,where articles coated with adhesive coating film are used, owing to theuse of radiation-curable coating materials, especially electronbeam-curable coating materials.

The coating film of the invention is particularly suitable for coatingworkpieces made, for example, from MDF (medium density fiberboard), andin terms of its chemical resistance in accordance with DIN 68861 Part 1it meets the conditions of resistance group 1A with respect to acetone,but at least those of resistance group 1B. In the crosshatch test inaccordance with DIN 53151 at least the characteristic value Gt 2C isreached, and the flexibility is sufficient in order to allow hotpressing around a rounded edge without breaking.

Adhesive

The connection of the adhesive layer (adhesive) on the self-supportingcoating film to said self-supporting coating film, on the one hand, andto the surface of the workpiece, on the other hand, is sufficientlyfirm, following the hot-pressing of the adhesive coating film, that whena self-adhesive tape stuck on forcefully and left for 72 hours is peeledoff sharply there is no adhesive fracture.

The acrylate adhesive used is, in particular, an internallycrosslinkable and, through the admixture of a polyfunctional isocyanate,externally reactive copolymer comprising softening and hardeningacrylate monomers and with a markedly weak surface tack (controlledtack).

The adhesive can be applied to the cured coating film by spreading itfrom solution on a coating unit using a coating knife, and evaporatingthe solvents in a drying tunnel.

Good adhesion of the adhesive to the coating material can be achieved byblending the adhesive with from 0.5 to 3, especially 1-2% by weight ofan isocyanate having an isocyanate content of from 20 to 24% by weightand partially reacting the isocyanate with free functional groups of thecoating material, during the drying of the adhesive on the coatingsurface and during the storage of the finished product. As the freefunctional groups of the coating material, OH groups, preferably COOHgroups, have been found most effective. To improve the anchoring of theacrylate copolymer on the coating material it has also been foundadvantageous for this copolymer to be dissolved in a solvent, whichswells the coating surface in the course of coating. As solvents forthis purpose, ketones are particularly suitable.

The adhesion of the adhesive on the coating surface is advantageouslyimproved by subjecting said surface to corona pre-treatment.

A sufficient adhesion of the adhesive-treated coating film to thesubstrate (surface of the workpiece) can be achieved by hot pressing onthe workpiece at a temperature of from 120 to 160° C., preferably from135 to 150° C., and a pressure of from 10 to 50 bar, preferably from 20to 40 bar, and over a period of from 1 to 4 minutes, preferably from 2to 3 minutes.

The adhesive can be crosslinked by forming a salt from is the centralmetal atom of a chelate complex with the free carboxyl groups of thecopolymerized acrylic acid at temperatures of 100° C. or more. Theproportion of acrylic acid is, in particular, between 3 to [sic] 8% byweight. An inner complex based on acetyl acetone, formed with titaniumor aluminum, can be used as crosslinking agent. From 0.1 to 0.6, inparticular, and preferably from 0.1 to 0.4% by weight of this agent areemployed.

The further crosslinking can take place by partial reaction of theisocyanate, optionally incorporated into the adhesive by mixing, withits acidic groups.

The crosslinking of the adhesive should be sufficiently high that thereis no shearing of said adhesive under slight stresses which may build upwithin the coating film as a result of pressing.

The reduced surface tack (controlled tack) of the acrylate copolymer canbe obtained by copolymerizing from about 15 to 50% of tertiary butylacrylate and/or from 5 to 30% of methyl methacrylate, depending on thedesired extent of the controlled tack.

Preparation

1. Coating of an auxiliary backing, preferably polyester film, in athickness of from 35 to 100 μm, preferably 50 μm, with an (electron)beam-curable coating material in a coat thickness of from 40 to 100 μm,preferably from 70 to 80 μm. Crosslinking of the coating, in particularon an EBC unit of the scanner type at from 50 to 100 kGy, preferably 80KGy [sic]. The accelerator voltage is about 350 kV.

The auxiliary backing can have a glossy or a matt surface. Accordingly,the subsequent visible side of the coating film will be either glossy ormatt. The auxiliary backing can easily be peeled off from the coatingsurface, but should remain thereon in particular until after thepressing of the adhesive coating film.

2. Coating of the free coating surface with an adhesive in a coatthickness of from 25 to 70 μm, preferably from 30 to 40 μm.

3. In the case of the use of an adhesive having a tacky surface,covering thereof with an antiadhesively treated paper or with acorresponding film.

As the adhesive it is also possible to employ a two-pack laminatingadhesive, especially one which in the finally crosslinked staterepresents a non-self-adhesive, weakly crosslinked polyurethane which isstill heat-plastifiable. It is preferably prepared from a prepolymerwhich contains isocyanate groups, and which is mixed with an at leastbifunctional alcohols [sic] based on ether or ester, preferably with apolyetherol having a hydroxyl content of from 20 to 32%, and aftercoating is crosslinked in situ on the coating surface. In the course ofthis crosslinking, the free isocyanate groups of the prepolymer reactpartially with functional groups of the coating surface.

The two-pack laminating adhesive is in particular a prepolymer whichcontains isocyanate groups and which is crosslinked with a diol.Crosslinking can take place in situ on the coating surface partiallyduring the drying of the adhesive, but mainly during the storage. of theready-prepared adhesive coating film.

The two-pack laminating adhesive used can in particular be onecomprising a prepolymer which contains isocyanate groups, is to bebrought to reaction with diethylene glycol and is based on a polyesterurethane comprising an aromatic isocyanate and with an isocyanatecontent of from 3 to 4%. The mixing ratio of prepolymer to diethyleneglycol is preferably 50 to 1 (parts by weight). The two-pack laminatingadhesive is preferably dissolved/employed at a strength of 60% in ethylacetate.

In particular, the two-component laminating adhesive has undergone finalcrosslinking even prior to pressing. The effect of its balancedcrosslinking density is firstly to allow sufficient wetting of thesurface of the workpiece in the course of pressing and secondly meansthat its cohesion is sufficiently high at the temperature at which theworkpiece is subsequently used. The two-pack adhesive can also be aprepolymer in the above sense which contains isocyanate groups and iscrosslinked with a phenolic resin/epoxy resin condensate. In this casethere is partial crosslinking of the adhesive during drying on thecoating surface and during subsequent storage of the product, as aresult of reaction of the free isocyanate groups of the prepolymer withthe secondary hydroxyl groups of the phenolic resin/epoxy resincondensate. In this case the free isocyanate groups of the prepolymerreact partly with the functional groups of the coating material. Theultimate crosslinking of the adhesive, which up to that point is stillheat-plastifiable, takes place in the course of the subsequent pressingof the product at relatively high temperatures, as a result of reactionof the epoxide groups with those molecular segments of the adhesive thatcarry active hydrogen atoms. At the same time there are likewiseadhesion-promoting reactions with the coating surface. Otherwise, withregard to processing, configuration of products employed and otherdetails, reference is made to the other exemplary indications.

In the text below the invention is described further with reference tothe examples.

A. Preparing the coating material

EXAMPLE 1

39.8 parts of the urethane acrylate of the invention, 80% inphenoxyethyl acrylate, 9.9 parts of acrylicized polyol, 14.9 parts ofisobornyl acrylate, 9.9 parts of ethoxyllated penthaerythritoltetracrylate [sic], 24.9 parts of TiO₂ pigment, 0.3 parts of emulsifier,0.3 parts of dispersing auxiliary.

The components are weighed out into the containers customary in thecoatings industry and are combined using a dissolver.

EXAMPLE 2

61.5 parts of the urethane acrylate of the invention are charged to avessel and at 50° C. are mixed with 13.4 parts of polyether acrylate. At50° C., 7.2 parts of vinylcaprolactam, 10 parts of isobornyl acrylate,are stirred in in the stated sequence.

The following process steps are carried out under the exclusion ofdirect incident sunlight. At 50° C., 4 parts of aliphatic urethaneacrylate [lacuna] stirred in. Subsequently, [lacuna] with 3.4 parts ofisobornyl acrylate. The mixture is subsequently adjusted to a viscosityof 6,900+/−1,500 mPaS [sic] (23° C.). The resin solution is stirredthoroughly at 50° C. for one hour more, filtered hot through a 1 μmfilter, and dispensed.

EXAMPLE 3

64.9 parts of the urethane acrylate of the invention are charged to avessel. At 50° C., 6 parts of vinylcaprolactam, 3.8 parts oftripropylene glycol diacrylate and 16 parts of hexanediol diacrylate arestirred in in the stated sequence. The following process steps arecarried out under exclusion of direct incident sunlight:

At 50° C., aliphatic urethane acrylates are stirred in (4 parts) and themixture is adjusted with 4.B parts of hexanediol diacrylate to aviscosity of 6,500+/−1,500 mPaS [sic].

The resin solution is subsequently stirred thoroughly at 50° C. for onehour, filtered through a 1 μm filter, and dispensed.

EXAMPLE 4

55 parts of the urethane acrylate of the invention are charged to avessel and are mixed at 50° C. with an aliphatic urethane acrylate (8parts). At 50° C., 5.5 parts of tripropylene glycol diacrylate, 7 partsof vinylcaprolactam, 16 parts of isobornyl acrylate are stirred in inthe stated sequence.

With exclusion of direct incident sunlight, 4 parts of aromaticisobornyl acrylate are stirred in at 50° C. in the stated sequence. Withexclusion of direct incident sunlight, 4 parts of aromatic urethaneacrylate are stirred in at 50° C., and the mixture is adjusted with 4parts of isobornyl acrylate to a viscosity of 7,500+/−1,500 mPaS [sic].The resin solution is subsequently stirred at 50° C. for one hour,filtered hot through a 1 μm filter, and dispensed.

EXAMPLE 5

54.3 parts of the urethane acrylate of the invention are charged to avessel and mixed at 50° C. with 7.9 parts of aliphatic urethaneacrylate. At 50° C., 5.3 parts of tripropylene glycol diacrylate, 7parts of vinylcaprolactam, 17 parts of isobornyl acrylate are stirred inin the stated sequence. With exclusion of sunlight, a photoinitiator isstirred in at 50° C. (4 parts) and the mixture is adjusted with 4 partsof isobornyl acrylate to a viscosity of 7,500+/−1,500 mPaS [sic].

The resin solution is subsequently stirred thoroughly at 50° C. for onehour, filtered hot through a 1 μm filter, and dispensed.

B. Preparing the coating film

1. A matt polyethylene terephthalate film having a reflectometer valueof 35 measured at an incident angle of 60° and having a thickness of 50μm is coated on a coating unit by means of a doctor blade with asolvent-free, electron beam-curable coating material in accordance withExamples 1-5 in a coat thickness of 80 μm.

2. The polyethylene terephthalate film coated with the liquid,solvent-free coating material is supplied to an electron beam unit ofthe scanner type where the coating material, without cooling, is curedunder inert gas with 80 kGy at an accelerator voltage of 350 kV.

3. The free coating surface of the resulting, readily detachablecoating/film laminate is coated with an adhesive in a coat thickness of30 μm either immediately in-line or separately by means of a doctorblade. Prior to the application of the adhesive, the coating surface issubjected to a corona pretreatment.

4. The adhesive is an acrylate copolymer comprising n-butyl acrylatewith 5% by weight of acrylic acid. In order to prevent the disruptivesurface tack, the monomers are copolymerized with 20% by weight oftert-butyl acrylate and 15% by weight of methyl methacrylate. For theinternal crosslinking of the adhesive an amount of 0.4% by weight ofaluminum acetylacetonate is added to the copolymer, and 1% of apolyfunctional polyisocyanate, prepared by trimerizing hexamethyleneisocyanate and having an isocyanate content of 21% by weight, is addedto the blend in order to increase its reactivity with respect to thecoating surface. The adhesive is employed as a 20% strength by weightsolution and as solvents contains acetone and isopropanol in a ratio of3:1.

5. The coating material coated with an adhesive subsequently passesthrough a drying tunnel in which the solvents are evaporated over aperiod of from 1 to 4 minutes at a temperature of from 70 to 100° C.

6. The dried, only partly crosslinked and still largelyisocyanate-reactive adhesive is covered with a siliconized paper or witha siliconized polyethylene film.

7. The resulting composite product is wound up into a roll and can bestored. In the course of storage, the adhesion-promoting reaction takesplace between the free isocyanate in the adhesive and the functionalgroups of the coating material.

C. Coating example

An adhesive coating film produced in this way can be joined permanentlyto the surface of a medium density fiberboard as follows:

1. The adhesive coating film is cut to the size of the workpiece that isto be coated.

2. The covering paper or the covering film are [sic] removed.

3. The adhesive coating film is placed onto the medium densityfiberboard workpiece, with the adhesive side facing the side of theworkpiece that is to be coated. Since the adhesive possesses acontrolled tack, it is easy to position and correct the adhesive coatingfilm. The polyester film is not removed from the visible side of thecoating material.

4. Then, the adhesive coating film is pressed onto the medium densityfiberboard at 40 bar and 150° C. for 3 minutes using a flatbed press.

The partly crosslinked but still flowable acrylate polymer, which underthe application of pressure wets the surface of the workpiece, undergoesits actual crosslinking in the course of pressing at the specifiedtemperature and hence acquires the cohesion necessary for the subsequentservice of the workpiece.

5. Following the pressing and the cooling of the workpiece, the mattpolyester film can be peeled off from the visible side of the coatingmaterial. It is advisable, however, not to remove the polyester filmfrom the coating surface of the coated workpiece during its subsequenthandling, since the film is able to ideally protect said surface up tothe point of final use.

6. A coated workpiece is obtained which has a flawless, matt surfacewhich meets the specified requirements.

What is claimed is:
 1. An adhesive coating film consisting of a) aradiation-cured coat comprising from 40 to 90% by weight of urethaneacrylate, from 0 to 20% by weight of polyether acrylate, from 10 to 50%by weight of reactive diluent, from 0 to 30% by weight of pigments of acarboxy-functional (meth)acrylic ester, from 0 to 10% by weight of othercustomary coatings fillers, and from 0 to 10% by weight ofphotoinitiator, and b) the radiation cured coat having on one side anadhesive composition, the adhesive composition comprising free NCOgroups when freshly applied, controlled surface tack, and the ability tobe thermally plastified.
 2. The adhesive coating film of claim 1,consisting of the reactive diluent comprises a member selected from thegroup consisting of vinylcaprolactam, tripropylene glycol diacrylate,hexanediol diacrylate, isobornyl acrylate, trimethylolpropanetriacrylate, pentaerythritol tetraacrylate, ethoxylated derivativesthereof, propoxylated derivatives thereof, and mixtures therof.
 3. Theadhesive coating film of claim 1, consisting of the urethane acrylateconsisting of from 30 to 45% by weight of polyester, from 0.01 to 0.1%by weight of catalyst, from 0.05 to 0.1% by weight of stabilizer, from10 to 20% by weight of hydroxyethyl acrylate, from 15 to 25% by weightof reactive diluent and from 20 to 35% by weight of diisocyanatecomponents.
 4. The adhesive coating film of claim 3, consisting of thepolyester consisting of from 50 to 75% by weight of alcohol, from 20 to50% by weight of acid, and 5% by weight of customary auxiliaries.
 5. Theadhesive coating film of claim 1, consisting of the polyether acrylateconsisting of from 50 to 75% by weight of a polyether polyol, from 2050% by weight of acrylic acid, and 5% by weight of customaryauxiliaries.
 6. The adhesive coating film of claim 5, wherein thepolyether polyol consists of an ethoxylated erythritol having amolecular weight of from 500 to 1,000.
 7. The adhesive coating film ofclaim 1, wherein the adhesive composition comprises an acrylate adhesiveconsisting of an internally crosslinkable and externally reactivecopolymer comprising softening and hardening acrylate monomers.
 8. Theadhesive coating film of claim 1, wherein the adhesive compositioncomprises a two-pack laminating adhesive.
 9. The adhesive coating filmof claim 1, consisting of the radiation-cured coat comprising freefunctional groups.
 10. The adhesive coating film of claim 7, wherein theacrylate adhesive comprises 2.5-8% by weight of acrylic acid.
 11. Theadhesive coating film of claim 7, wherein the acrylate adhesivecomprises a member selected from the group consisting of from 15 to 50%by weight of copolymerized tertbutyl acrylate, from 5 to 30% by weightof copolymerized methyl methacrylate, and mixtures thereof.
 12. Theadhesive coating film of claim 7, wherein the acrylate adhesivecomprises 0.1-0.6% by weight of a metal chelate complex.
 13. Theadhesive oating film of claim 7, wherein the acrylate adhesive 0.5-3% byweight of a polyfuctional polyisocyanate.
 14. A process for producingthe adhesive coating film of claim 1, coating an auxiliary backing witha radiation-curable coating material, curing the coating material byradiation to provide a free coated surface, coating the free coatedsurface with an adhesive.
 15. A method of coating a substrate,comprising providing the adhesive coating film of claim 1, providing asubstrate selected from the group consisting of metal, plastic, paper,cardboard, wood, glass, glass fibers and mixtures thereof, and applyingthe adhesive coating film to the substrate.
 16. An adhesive coating filmconsisting of a) a radiation-cured coat comprising from 50 to 60% byweight of urethane acrylate, from 10 to 15% by weight of polyetheracrylate, from 25 to 40% by weight of reactive diluent, from 2 to 5% byweight of a carboxy-functional (meth)acrylic ester, from 0 to 10% byweight of other customary coatings fillers, and from 3 to 6% by weightof photoinitiator, and b) the radiation cured coat having on one side anadhesive composition, the adhesive composition comprising free NCOgroups when freshly applied, controlled surface tack, and the ability tobe thermally plastified.
 17. The adhesive coating film of claim 16wherein the radiation cured coat is cured with UV radiation.
 18. Theadhesive coating film of claim 4, consisting of the polyester consistingof from 55 to 65% by weight, of alcohol, from 30 to 45% by weight ofacid, and 5% by weight of customary auxiliaries.
 19. The adhesivecoating film of claim 5, consisting of the polyether acrylate consistingof from 55 to 65% by weight, of a polyether polyol, from 30 to 45% byweight, of acrylic acid, and 5% by weight of customary auxiliaries. 20.The adhesive coating film of claim 6, wherein the polyether polyolconsists of an ethoxylated erythritol having a molecular weight of from700 to
 900. 21. The adhesive coating film of claim 8, wherein theadhesive composition comprises a two-pack laminating adhesive which is aweakly crosslinked polyurethane which is non-self-adhesive and stillplastifiable in the final crosslinked state.
 22. The adhesive coatingfilm of claim 9, consisting of the radiation-cured coat comprising freefunctional groups selected from the group consisting of OH groups, COOHgroups and mixtures thereof.
 23. The adhesive coating film of claim 10,wherein the acrylate adhesive comprises 2.5-5% by weight of acrylicacid.
 24. The adhesive coating film of claim 11, wherein the acrylateadhesive comprises a member selected from the group consisting of from20 to 40% by weight of copolymerized tertbutyl acrylate, from 10 to 15%by weight of copolymerized methyl methacrylate, and mixtures thereof.25. The adhesive coating film of claim 12, wherein the acrylate adhesivecomprises 0.1-0.4% by weight of a metal chelate complex selected fromthe group consisting of a titanium chelate complex, an aluminum chelatecomplex or mixtures thereof.
 26. The adhesive coating film of claim 25,wherein the acrylate adhesive comprises aluminum acetylacetonate. 27.The adhesive coating film of claim 13, wherein the acrylate adhesivecomprises 1-2% by weight of a polyisocyanate obtained by trimerizinghexamethylene diisocyanate and having an isocyanate content of 20-24% byweight.
 28. The process of claim 14, further comprising removing theauxiliary backing.
 29. The process of claim 28, wherein the auxiliarybacking is removed prior to the coating with adhesive.
 30. The processof claim 28, wherein the auxiliary backing is removed after the coatingfilm is adhesively bonded.